Microbial community of anaerobic digestion of rice straw enhanced by amino acid ionic liquid

This study proposes a novel method to enhance methane production from anaerobic digestion using an amino acid-derived ionic liquid, glycine hydrochloride ([Gly][Cl]). After 40 days of digestion with 5% [Gly][Cl], the cumulative methane production was 115.56 mL/g VS, which was 73% higher than that of the control group (without additive). [Gly][Cl] specifically stimulated the activities of protein-hydrolyzing and acid-producing bacteria. Moreover, the peak activities of cellulase, xylanase, and lignin peroxidase were significantly higher than those of the control group. The addition of [Gly][Cl] increased bacterial diversity and reduced archaeal diversity. Specifically, Synergistota represented by Syner-01, Fibrobacterota represented by BBMC-4, Bacteroides, and unclassified_f__Lachnospiraceae significantly increased in relative abundance. It also increased the abundance of methanogens and archaea, converting more substrates to methane. Therefore, [Gly][Cl] can improve methane yield as an anaerobic digestion additive.